6. Vitamins Flashcards
What are the general characteristics of vitamins?
- Organic compounds w/ regulatory functions
- Cannot be synthesized in sufficient quantities by the body –> must be obtained from the diet
How many vitamins are universally recognized?
13
What is the classification of vitamins based on? What is it not based on?
By their biological and chemical activity, not their structure
What is a vitamer?
A form of a particular vitamin
What are the main classifications of vitamins?
- Water-soluble
- Fat-soluble
How many water-soluble vitamins are there?
9
How many fat-soluble vitamins are there?
4
How are water-soluble vs. fat-soluble vitamins handled in the body?
- Water soluble vitamins are not stored
- Fat soluble vitamins can be stores, but not all are stored
What is the one water soluble vitamin that can be stored? Where is it stored?
Vitamin B12 can be stored in the liver for long periods of time
What is the toxicity of water soluble vs. fat soluble vitamins at excessive doses?
- Water soluble = mostly non-toxic at excessive doses
- Fat soluble = most are toxic at excessive doses
List the fat-soluble vitamins?
A, D, E, K
What type of vitamins do not undergo digestion? Why not?
Water-soluble vitamins are small enough to be absorbed
What mechanisms does the digestive tract use to move water-soluble nutrients from your gut to your bloodstream?
- Sodium-dependent active transport
- Diffusion
In what forms are water-soluble vitamins transferred throughout the bloodstream?
- Free-form (not bound to anything)
- Bound to specific protein carriers
- Bound to albumin
What organ continuously regulates levels of water-soluble vitamins? What does it do w/ the excess?
Kidneys excretes excesses out of body in your urine
How often should water-soluble vitamins be replenished?
Every few days
In what form is vitamin C primarily found as?
Ascorbic acid
What are the common sources of vitamin C?
Fruits and veggies
What is the RDA of vitamin C for men vs. women?
- Men = 90 mg/day
- Women = 75 mg/day
What are the functions of vitamin C?
- Collagen synthesis
- Antioxidant activity
- Neurotransmitter synthesis
- Enhances immune function when you have a cold
- Protects against certain types of cancers
- Helps prevent CV disease by maintaining integrity of vasculature
What condition does vitamin C deficiency lead to? Symptoms?
SCURVY = issues w/ healing, bleeding, bruising, hair health, brain health
- hyperkeratosis of hair follicles
- hypochhondriasis (psychological manifestations)
- retarded wound healing
- bleeding gyms
- spontaneous rupture of capillaries
What are the consequences of vitamin C toxicity?
Minor side effects from supplements = GI tract issues
-diarrhea, nausea, vomiting, heartburn, bloating, headache, insomnia, kidney stones
How does one get too much vitamin C? (toxicity)
From supplements, not usually from diet
What are the common sources of thiamin?
- Meats (pork)
- Legumes
- Enriched grains
- Fortified foods
What is the RDA of thiamin for men vs/ women?
- Men = 1.2 mg/day
- Women = 1.1 mg/day
What are the functions of thiamin?
- Energy transformation (coenzyme role)
- Synthesis of pentoses and NADPH (coenzyme role)
- Membrane and nerve conduction (non-coenzyme capacity)
What condition does a thiamin deficiency lead to? Symptoms?
BERIBERI
- muscle weakness
- anorexia
- tachycardia
- enlarged heart
- edema
What are the diff types of beriberi? What does each effect?
- Dry: affects peripheral nervous system
- Wet = affects CV system
What foods can inhibit thiamin absorption?
Alcohol, coffee, tea, raw fish
What type of prob is the Wernicke-Korsakoff syndrome?
Neurologic and psychiatric problems
What is the danger of thiamin toxicity? At what dosage does this occur? Symptoms?
- Little danger w/ oral intake
- Toxicity probs only seen in doses 5000x higher than RDA
- Sx: nerve and CV issues
What are the common sources of riboflavin?
- Milk/dairy
- Eggs
- Meat
- Liver
- Legumes
- Fortified grains
What is the RDA of riboflavin for men vs. women?
- Men = 1.3 mg/day
- Women = 1.1 mg/day
What are the functions of riboflavin?
Coenzyme that participates in several rxns to release e- from carbs, fat, ketones, and protein through the Krebs cycle and carry them tot he ETC for energy production
What condition does a deficiency in riboflavin lead to? Symptoms?
Ariboflavinosis
- cheilosis (cracks at corners of mouth)
- glossitis (painful, red tongue)
- Photophobia (sensitivity to light)
- Edema (swelling)
What are the common sources of niacin?
- Fish and meats
- Enriched grains
- Peanut butter
What is the RDA of niacin for men vs. women?
- Men = 16 mg/day
- Women: 14 mg/day
What has the highest RDA of all the B-vitamins?
Niacin (B3)
What are the functions of niacin?
- Coenzyme in redox rxns (oxidative rxns, reductive biosynthesis)
- Component of NAD, which is used in glycolysis and the TCA cycle to carry electrons to the ETC
What condition does a niacin deficiency cause?
Pellagra
- dermatitis
- diarrhea
- dementia
- death
What are the consequences of niacin toxicity? Symptoms?
Niacin flush = skin flushing and itching, dry skin, skin rashes including eczema exacerbation
What are the common sources of pantothenic acid?
Virtually all foods (organ meats, mushrooms, broccoli, avocados, whole grains, sunflower seeds, peanuts)
What is the RDA of pantothenic acid?
5 mg/day
What are the functions of pantothenic acid?
- Major component of coenzyme A (nutrient metabolism)
- Acetylation of proteins, sugars, drugs
What are the consequences of pantothenic acid deficiency?
- Fatigue, insomnia, depression, irritability
- Burning feet syndrome (caused by neuropathy)
- usually occurs w/ other B vitamin deficiencies
What are the common sources of pyridoxine?
- Animal products (sirloin, salmon, light meat chicken)
- Plant foods
- Fortified cereals
- Supplements (for vegetarians)
What is the RDA of pyridoxine for men vs/ women?
1.3 mg/day
What are the functions of pyridoxine?
- In the form PLP, needed to convert AAs to glucose (gluconeogenesis)
- Coenzymes
- Noncoenzymes
What types of individuals are at higher risk for pyridoxine deficiency?
- Elderly
- Alcoholics
- People on certain drugs
What are the consequences of pyridoxine toxicity?
Sensory and peripheral neuropathy
What are the consequences of pyridoxine deficiency?
Sensory and peripheral neuropathy (nerve pain in extremities)
What are the common sources for biotin?
- Widely distributed in foods (beef, soybeans, egg yolk)
- Made by bacteria in large intestine
How much biotin does a person need per day?
30 micrograms/day
What are the functions of biotin?
- Coenzyme roles (FA synthesis, gluconeogenesis, carboxylation rxns)
- Non-coenzyme roles (biotinylation, gene expression, cell cycle
What would cause a biotin deficiency?
Genetic mutation biotinidase deficiency
Folate vs. Folic acid
- Folate: reduced form found naturally in foods and tissues
- Folic acid: oxidized form found in fortified foods/supplements
What are the common sources of folate?
- Mushrooms
- Green veggies
- Enriched foods
What is the RDA of folate?
400 micrograms/day
Why is folate so important for pregnant women?
Woman who take folic acid supplements before and during early pregnancy can prevent 50% or more of neural tube defects
What are the functions of folate?
- AA metabolism
- Purine and pyrimidine synthesis, nucleotide metabolism
What are the consequences of folate deficiency?
- Megaloblastic macrocytic anemia
- Neural tube defects in babies of pregnant woman
What are the common sources for vitamin B12?
- Meat
- Shellfish
- Dairy products
- Supplements
What is the RDA of vitamin B12?
2.4 micrograms/day
How is vitamin B12 absorbed?
- Vitamin B12 released from food
- Vitamin B12 binds to R proteins in saliva and gastric juice
- In small intestine, R protein is digested to release vitamin B12
- Vitamin B12 binds to intrinsic factor (IF), forming a complex in small intestine
- Vitamin B12-IF complex binds to a receptor on enterocytes in the ileum and gets internalized by endocytosis
What are the functions of vitamin B12?
- Brain and nervous system health
- Formation of blood
- Conversion of homocysteine to methionine (methylcobalamin)
- Conversion of L-methylmalonyl CoA to succinyl CoA (adenosylcobalamin)
What are the consequences of vitamin B12 deficiency? Cause
- Megaloblastic marocytic anemia
- Neuropathy
- usually caused by inadequate absorption of vitamin B12
What are the different types of vitamin A?
- Retinoids
- Carotenoids
What are the common sources of retinoids?
Foods of animal origin (liver, dairy, eggs, fish oils, tuna)
What are the common sources of carotenoids (provitamin A)?
Food of plant origin (fruits & vegetables)
What is the RDA of vitamin A for men vs. women?
- Men = 900 micrograms RAE
- Women = 700 micrograms RAE
What are the different forms of carotenoids?
- Beta-carotene
- Alpha-carotene
- Gamma-carotene
How is the majority of vitamin A absorbed? What % of vitamin A is absorbed this way?
70-90% absorbed from a fat-containing meal b/c vitamin A is fat-soluble
How much carotenoid absorption occurs when eating uncooked veggies by themselves?
5%
What are the functions of vitamin A?
- Vision
- Gene expression
- Cellular differentiation
- Immune health
- Bone metabolism
Describe the function of carotenoids?
Antioxidants –> have the ability to react w/ and quench (inactivate) free radical rxns
What are the consequences of vitamin A deficiency?
Night blindness, Bitot’s spots
How prevalent is vitamin A deficiency around the world?
Approx 1/3 of children under the age of 5 around the world
What are the consequences of vitamin A toxicity?
- Teratogenic
- Damaged liver
- Orange discoloration of skin
What are the common sources of vitamin D?
- Synthesis in skin from sunlight
- Meat
- Dairy
- Some saltwater fish
- Fortified foods like milk, cereals
What is the RDA for vitamin D?
15-20 micrograms
How is vitamin D absorbed and transported?
- Absorbed from micelles w/ help from fat and bile salts by passive diffusion
- Incorporated into chylomicrons for transport into lymphatic system, then into blood
How can our bodies synthesize vitamin D?
Can synthesize a vitamin D precursor from cholesterol, which then needs to be activated by exposure to sunlight
What are the functions of vitamin D?
- Regulates BP and decreases risk of heart disease
- May improve blood glucose in diabetics
- Decreases calcium loss in urine, increase calcium absorption in intestine, increase bone mineralization
What are the consequences of vitamin D deficiency?
- Myopathy (muscle disease)
- Autoimmune disorders
What are the consequences of vitamin D deficiency in children vs. adults? Symptoms?
- Children: rickets (seizures, growth retardation, bones don’t mineralize)
- Adults: osteomalacia (poor bone mineralization)
How is vitamin D deficiency treated?
Supplement
What is vitamin D toxicity caused by? Not caused by?
Supplements, not the sun
What are the 2 classes of vitamin E?
- Tocopherols
- Tocotrienols
What form of vitamin E has the highest bioactivity?
Alpha-tocopherol
What are the common sources of vitamin E?
- Plant oils (canola, olive, sunflower, cottonseed)
- Whole grains
- Legumes
- Some fruits and veggies
What is the RDA of vitamin E?
15 mg/day
What are the roles of vitamin E?
Antioxidant role:
-maintains membrane integrity of body cells
-free radical termination
Prevent heart disease:
-may inhibit oxidation of LDL and prevent blood clots
What are the consequences of vitamin E toxicity?
GI distress and bleeding
What are the consequences of vitamin E deficiency?
- Skin probs
- Lipid oxidation probs
- Cell membrane probs
What are the 3 forms of vitamin K?
- Phylloquinones
- Menaquinones
- Menadiones
What are the sources of phylloquinones?
Plants (green, leafy veggies)
What are the sources of menaquinones?
Bacteria (fermented products)
What is the adequate intake amount of vitamin K for men vs. women?
- Men = 120 micrograms/day
- Women = 90 micrograms/day
What are the functions of vitamin K?
- Blood clotting
- Bone health
- Carboxylation of glutamic acid residues
What are the consequences of vitamin K deficiency?
Probs w/ blood clotting
Which vitamins are most involved in hematopoiesis (production of blood cells)?
- Folate
- Pyridoxine
- Vitamin B12
- Pantothenic acid
Vitamin C acts as a water-soluble antioxidant which can assist in the regeneration of which other antioxidant vitamin?
Vitamin E
List the vitamins in order of highest to lowest RDA.
- Vitamin C = 75-90 mg/day
- Niacin (B3) = 14-16 mg/day
- Vitamin E = 15 mg/day
- Pantothenic acid (B5) = 5-6 mg/day
- Pyridoxine (B6) = 1.3-1.7 mg/day
- Riboflavin (B2) = 1.1-1.3 mg/day
- Thamin (B1) = 1.1-1.2 mg/day
- Vitamin A = 700-900 micrograms/day
- Folate = 400 micrograms/day
- Vitamin K = 90-120 micrograms/day
- Biotin = 30 micrograms/day
- Vitamin D = 15 micrograms/day
- Cobalamin (B12) = 2.4 micrograms/day
By what carrier do fat-soluble vitamins get absorbed?
Micelles
Where are most vitamins stored?
Liver
What does vitamin B12 require for absorption?
Intrinsic factor
What is the vitamin that is best known for imparting a yellow/orange color to urine?
Riboflavin
